The space group and diffraction extent of the crystalline complex between an antibody FAB and its antigen, Il4 were determined. Diffraction to 4.0 Angstroms was observed on beam line A-1. Severe decay problems, probably related to flash freezing conditions, limited the extent of useful data measured. Additional data were recorded from several herpes family viral serine proteases. These data extended to 2.2 Angstroms and were subsequently used to solve the structure of cytomegalovirus protease. Data from a novel human cysteine protease, cathepsin K, were recorded at 1.7 Angstroms resolution.